Most people sleep in the position they find most comfortable. The best sleeping posture is lying flat on your back, facing the ceiling. This allows your body weight to be evenly distributed and helps maintain proper spinal alignment. However, if you can only fall asleep on your side, which side should you choose?
The answer depends on your physical condition.
If you suffer from acid reflux, sleeping on your left side is better. Research from the University of Amsterdam found that sleeping on the left side significantly reduces the amount of stomach acid that reaches the esophagus. This is because the stomach is positioned more toward the left side of the body. When you lie on your left, food naturally moves downward, aiding digestion. On the other hand, lying on your right can make the stomach higher than the esophagus, increasing the likelihood of acid reflux.
For constipation, sleeping on your left side is also helpful. Sleep expert Dr. Lisa Artis explained that this position uses gravity to help move food and waste smoothly from the small intestine to the large intestine, promoting bowel movements. In contrast, if you have diarrhea, sleeping on your right side can help. When you lie on your right, waste remains longer in the ascending colon, allowing more time for water absorption and reducing stool frequency.
Pregnant women are also advised to sleep on their left side. As the uterus enlarges in the middle and late stages of pregnancy, it can press on nearby organs and blood vessels. The body’s largest vein, the inferior vena cava, runs along the right side, so lying on the left reduces pressure on it. Sleeping on the right may restrict blood circulation, leading to high blood pressure, swelling, or reduced blood flow to the fetus. Even lying flat on your back can compress the aorta, so caution is needed.
No matter which side you prefer, placing a pillow between your knees can help maintain proper spinal alignment and reduce pressure on your hips and legs.
On the other hand, sleeping on your stomach should be avoided. This position strains the neck and shoulder muscles and forces the spine into an unnatural curve, potentially causing pain in the back, neck, and shoulders. Prolonged stomach sleeping also increases the risk of neck ligament damage and spinal deformities.
